The fashion designer Chi Zhang poses with a face mask which he designed, at his shop in Beijing on November 4, 2014. Zhang said China's air pollution is one of his prime inspirations and the embellished images of gas masks and the phrase "Fxxk Air Pollution" are trademarks in his creations. #

A before-and-after interactive pair of photos shows buildings on a polluted day, and a sunny day in Beijing. Pictures were taken on December 19, 2014, and January 15, 2015 (polluted). [Click on the image above to view transition.] #

A before-and-after interactive pair of photos shows a statue of China's late Chairman Mao Zedong on a polluted day, and a sunny day in Beijing. Pictures were taken on November 17, 2014 and January 14, 2015 (polluted). [Click on the image above to view transition.] #

A before-and-after interactive pair of photos shows statues of pandas on a polluted day, and a sunny day in Beijing. Pictures were taken on November 17, 2014 and January 14, 2015 (polluted). [Click on the image above to view transition.] #

A before-and-after interactive pair of photos shows China Central Radio and Television Tower (CCTV Tower) on a polluted day, and a sunny day in Beijing. Pictures were taken on December 19, 2014 and January 15, 2015 (polluted). [Click on the image above to view transition.] #

A before-and-after interactive pair of photos shows the Tiananmen Gate where the portrait of China's late Chairman Mao Zedong is displayed on a polluted day, and a sunny day in Beijing. Pictures were taken on November 17, 2014 and January 15, 2015 (polluted). [Click on the image above to view transition.] #

A before-and-after interactive pair of photos shows the National Grand Theatre, which has been nicknamed "The Egg," on a polluted day, and a sunny day in Beijing. Pictures were taken on November 17, 2014 and November 19, 2014 (polluted). [Click on the image above to view transition.] #

Liu Ke's mask, a new filter (right), and a used filter which he had used for two weeks sit on a table in Beijing on December 19, 2014. Liu rides a bicycle almost every day to avoid Beijing's congested traffic. He said it is necessary for him to wear a mask when air-pollution levels increase to protect himself. #

Yong Xiaoyan, wears a nose mask as she works at her office in Beijing on December 11, 2014. The office worker said she has used the mask every day since she found out she was pregnant and was concerned that Beijing's air pollution could harm her baby. The nose mask which was developed by a medical company can filter out tiny particles of pollution, the company said. #

Kong Ning wears a wedding dress decorated with 999 face masks for her performance art work, "Marry the blue sky," in front of the China Central Television (CCTV) Headquarters on a hazy day in Beijing on November 19, 2014. Wearing a 10-meter-long wedding dress decorated with face masks is a part of Kong Ning's performance art work which signifies her frustration with air pollution. #

Liu Ruiqiang measures the air quality with his particle counter on a balcony at his house, as his daughter looks on in Beijing on February 3, 2015. Ruiqiang put up with chronic smog in China's capital of Beijing, but he didn't want to take any chances when his daughter was born. The salesman now carries a handheld pollution sensor everywhere. On days when air pollution reaches hazardous levels, his toddler daughter is confined to their home, where a pair of constantly whirring air purifiers make it safer to breathe. #

A model shows a creation by the fashion designer Chi Zhang at a rehearsal for Chi Zhang's fashion show in Beijing on November 22, 2014. Zhang said China's air pollution is one of his prime inspirations. #

Liu Ke wears a mask as he carries his bicycle in Beijing on December 19, 2014. Liu rides a bicycle almost everyday to avoid Beijing's congested traffic. He said it is necessary for him to wear a mask when air pollution levels increase, to protect himself. #